Systems using an e-mail system and the Internet are known as common systems for data exchange.
In the conventional system, a transmission user exchanges data by individually specifying the reception partner by an address or a user identifier when exchanging data through an e-mail system. When the address or the user identifier is already known, the reception user also receives unnecessary messages from an unspecified transmission user.
In a website or a discussion board on the Internet, the transmission user can receive data owned by an unspecified number of transmission users, without specifying a communication partner individually each time. However, since there is no way to limit reception users accessible to data items uploaded on the website by the transmission user, all of data items uploaded on a website by the transmission user are treated as data items to be transmitted, and are open to an unspecified number of reception users.
As described above, the conventional technology is inconvenient to a transmission user in that the transmission user cannot provide data only to unspecified reception users who satisfy conditions preferred by the transmission user himself. In addition, the conventional technology is inconvenient to the reception user in that a data item necessary for the reception user cannot be received only from an unspecified transmission user who satisfies conditions preferred by the reception user.
The following techniques are presented as techniques for partially solving the problems.
PTL 1 discloses a technique in a system for sending e-mail after specifying a group address based on a mailing list, the technique being for automatically determining an address of a partner satisfying a predetermined condition when sending e-mail as a member belonging to a group address, and sending the e-mail.
PTL 2 discloses a system for collectively managing whether or not personal information can be disclosed by a disclosure route managing server as a method for controlling disclosure by disclosing information only when a right to disclose personal information exists, in order to prevent the personal information from leaking.
Conventionally, documents and data with keywords and classifications assigned are accumulated, and the documents and the data are selected for a search by specifying a keyword and a classification by a searcher. With this, unspecified searchers may be limited by a keyword or a classification.